Writing Equations of Parallel or Perpendicular Lines

Front

What is the equation of a horizontal line?

Back

y = b, where b is a constant.

Front

What is the equation of a vertical line?

Back

x = a, where a is a constant.

Front

What is the slope of a line?

Back

The slope (m) is the ratio of the rise (change in y) to the run (change in x).

Tags

CCSS.8.EE.B.5

Front

What does it mean for two lines to be parallel?

Back

Two lines are parallel if they have the same slope and different y-intercepts.

Tags

CCSS.8.EE.B.6

Front

What does it mean for two lines to be perpendicular?

Back

Two lines are perpendicular if the product of their slopes is -1.

Tags

CCSS.8.EE.B.6

Front

How do you find the slope of a line given two points (x1, y1) and (x2, y2)?

Back

Slope (m) = (y2 - y1) / (x2 - x1).

Tags

CCSS.8.EE.B.5

Front

What is the slope-intercept form of a line?

Back

The slope-intercept form is y = mx + b, where m is the slope and b is the y-intercept.

Tags

CCSS.8.EE.B.6

CCSS.8.F.A.3

Front

How do you write the equation of a line given a point and a slope?

Back

Use the point-slope form: y - y1 = m(x - x1).

Front

What is the relationship between the slopes of parallel lines?

Back

The slopes of parallel lines are equal.

Tags

CCSS.8.EE.B.5

Front

What is the relationship between the slopes of perpendicular lines?

Back

The slopes of perpendicular lines are opposite reciprocals.

Tags

CCSS.8.EE.B.6